The present invention relates to a device and a method for wiping a window.
Devices for wiping a window may have an electric motor, a mechanical system, as well as one or more wiper blades, which may be swivel-driven by an electric motor. In a motor vehicle, the wipers may swivel between an upper wiper blade end position, which may be located in the region of the A-pillar of the vehicle, and a lower wiper blade end position, which may be located at the lower edge of the windshield.
The mechanical system may include a crank drive made up of torque rods and connecting rods, which may be interconnected by bearings. Since, during operation of the wiper device, considerable bearing forces may be constantly exerted transversely to the bearing axis, it may be made from an especially high-quality material to prevent premature wear. Alternatively, the wiper blade end positions may be situated far enough from the A-pillar or the lower window edge, to compensate for displacements of this position due to wear.
According to an exemplary device and/or exemplary method of the present invention, a control device may compensate for clearances of the mechanical systems, which may become greater as the number of loads increases, due to wear. Since constant load changes may subject the crank drive bearings to wear, thereby degrading bearing quality, a shifting in the reversing position of the wiper blades on the window may occur with increasing age of the vehicle or with increasing age of the wiper device. These clearances of the mechanical systems may be compensated for with the aid of a control device according to an exemplary embodiment and/or exemplary method of the present invention, so that the wiper blades may return to the same position over the entire service life of the wiper device.
The clearance of the mechanical system as a function of service life may also be compensated, since vibrations that may occur during vehicle operation may also cause the bearing play to increase, due to the weight of the individual components of the wiper device.
An overlapping compensation as a function of load change and service life may be used.
The drive end positions, in which the reversible electric motor changes its direction of rotation, may be modified as a function of service life or with an increase in the number of load changes. This may enable the wiper blade end positions to be precisely maintained, without requiring expensive sensors in the region of the windshield or the wiper blades to detect the exact position of the wiper blades.
If the service life of the mechanical system is dependent upon the distance traveled by the vehicle, a separate time measuring device may not be required in the vehicle. The distance traveled by the motor vehicle may be obtained from the odometer of the motor vehicle.
The compensation may occur incrementally every fifty- to two-hundred thousand (e.g. every hundred thousand) wiping periods or load changes. In this manner, a compensation may only be implemented if a measurable difference between the desired wiper blade end position and the actual wiper blade end position is reached.
The control device may be configured such that a compensation may be effected every two- to ten-thousand kilometers. This may allow an incremental compensation, even if the vehicle is only used in fairly dry weather. In the case of cabriolets, which may be used in dry weather on secondary roads having uneven road surfaces, vehicle vibrations may be naturally more pronounced than on expressways.
Compensation may be allowed to occur continuously after each wiping period. In this manner, an optimal wiper blade end position may be maintained. Also, there may be no need for additional signals from the odometer, the clock or a wiper-period counter.
The control device may be configured such that only the upper wiper blade end position, in the region of the A-pillar, is subject to compensation. The area of the A-pillar may be the critical area in which the wiper blade, on the one hand, may need to be guided as closely as possible to the A-pillar in order to achieve as large a wiping field as possible, yet, on the other hand, may not touch the A-pillar, in particular during rapid wiping operation. However, this may happen if there is no compensation for the increase in the clearance of the mechanical system. This may not be as critical in the lower wiper blade end position, since this may be only of secondary importance to the driver""s field of vision.